Fired-up Puerto Ricans have pledged to come to New York to help Democratic nominee Fernando Ferrer become the city’s first Latino mayor, a key backer said yesterday.

“I have received 50 calls from people in Puerto Rico and down South who want to work on the campaign,” said Assemblyman José Rivera, the Bronx Democratic Party chairman. “Freddy’s candidacy has become big news in Puerto Rico. People are calling from all over.”

Rivera said some of the volunteers used to live in New York and were active in politics going back to the 1960s.

Ferrer, who is Puerto Rican, needs a huge turnout among Latinos in general to have any chance of defeating well-financed incumbent Mayor Bloomberg.